In the ancient time, the human honored the winged clan as gods for their ability to fly and to build a castle in the sky. The day when the castle was to be lifted off the ground an explosion destroyed it. A human girl was suspected to have the done it. However, a man from the winged clan didn't believe it and saved her life. As it turned out, it was a faction of the winged clan trying to start a war with the humans in order to expand their control.